Semiconductor devices are implemented in many different types of electrical products from digital cameras to handheld devices. In the manufacture of a semiconductor device, layers upon layers of various materials are stacked in succession with intertwined connections and carefully designed joint mechanism.
Devices are designed to have a more compact dimension, and the components have to shrink so as to fit into a relatively small space. In this regard, how the components are stacked or packed is critical in device size. Package on package (PoP) is developed to accommodate more components in a given area by well-organized stacking. The number of electronic components within a given area in the semiconductor device indeed increases, while the high component density is inevitably accompanied by an increase of input/output (I/O) number. The layout of PoP can have a great impact on the pitch that determines the I/O density, especially when it come to the joint mechanism. In other words, the bonding between the packages in a PoP structure can affect the dimensions of the electrical product to a great extent.